PHOSPHOR BRONZE WIRES. 
321 
NOTES ON CEETAIN ELASTIC PECULIARITIES OP 
PHOSPHOR BRONZE WIRES. 
L. P. SIEG AND A. J. OEHLER. 
Introduction . — Some previous work by one of the authors with 
wires of an alloy of platinum-iridium, portions of which work 
were published in these Proceedings,^ indicated that when the 
wires were used as suspensions for torsion pendulums, the rela- 
tions between the period of vibration and the amplitude were 
exceedingly complicated. The effect of drawing these wires was 
dealt with in another paper.^ In all these papers referred to, 
the statement was made that similar tests should be applied to 
some of the more common wires in the hope of finding similar, 
even though smaller effects. Through press of work these ex- 
periments have been deferred until the present year. This par- 
ticular paper' will 'dTeal with but of the work, namely, 
the effect of drawing on the elastic nature of phosphor bronze 
wires. The writers are indebted to the American Electrical 
Works, of Phillipsdale, Rhode Island, for kindly furnishing 
them with specimens of the wires. 
Significance of the work. — Physicists, and no doubt many 
others, will realize that it is highly important to know intimately 
tha elastia nature- of phosphor bronze wires on account of the 
fact that these wires are in such common use in the manufac- 
ture of delicate suspensions of all kinds, particularly for galva- 
nometers. Often, especially in absolute measurements, we depend 
on the general law for vibrating wires that the coefficient of 
simple rigidity determined statically be in agreement with 
the same coefficient determined kinetieally. This agreement is 
possible only where the wires follow the law that the period of 
vibration, in angular harmonic motion, is practically independ- 
ent of the amplitude. In fact the only thing, aside from internal 
friction of various sorts, that can affect the period should be ex- 
ternal air friction, and for reasonably slow periods this should 
not be a serious source of error. 
Ua. Acad, ol Sci., Proe. XVII, p. 185, XVEII, p. 115, XIX, p. 189 . 
2Phys. Rev. 35, 317, 1012. 
21 
